tcl programming exercises

TCL Scripting Training. and let's discuss it. Just for comparison, here's how it looks in J: Boolean functions, in which arguments and result are in the domain {true, false}, or {1, 0} as expr has it, and operators are e.g. Intro to Tcl: Exercises #2 Exercises #2 Rewrite the change function (Exercise 1.3) to work for any set of coins (or notes) for any decimal currency. The other words (arguments) are not substituted because they're curly-braced, so either 0 or 1 is invoked, and does its simple job. It was created by John Osterhout in 1988. one with at most one rule per state and input character), which gives clear instructions and two test cases for input and output, so I decided to try my hand in Tcl. The know command is called with a condition that should result in an integer when given to expr, and a body that will be executed if cond results in nonzero, returning the last result if not terminated with an explicit return. So 8 is the associated integer of a&&b, but not only of this we get the same integer for ! Ah, the joys of weekend Tcl'ing and belatedly, Happy Birthday, John! here is an implementation that even returns a list of the results of each iteration: using this, a string reverse function can be had as a one-liner: Another example is the following range-aware switch variation. # This simple but infinite stream source produces all positive integers: # This produces all (well, very many) powers of 2: # A filter that reads and displays a stream until user stops it: # Here is a sample usage with famous name: #. which uses the (less) famous function maker: # Usage example: more {grep this {cat streams.tcl}}. Tcl - Logical Operators. reports the results as wanted in the paper, on stdout: Streams are a powerful concept in (not only functional) programming. Here's a little debugging helper, to find out why "know" conditions don't fire: Now testing what new magic this handful of code allows us to do. "Hello, World!" is the traditional first program for beginning programming in a new language or environment. Practical Programming in Tcl and Tk by Brent Welch, Ken Jones. Compared to an RPN language, hypot would be. Called Logical AND operator. The numbers of the bits finally still set are supposed to be primes, and returned: Here's code to count the number of 1-bits in a bit vector, represented as an integer list. Sorting can be done when pushing, or when popping, and since our push is so nicely generic I prefer the second choice (as the number of pushs and pops should be about equal, it does not really matter). For instance, here's how to make an authors' index in four lines: gives us a books list of all authors matching the given glob pattern (we reuse Tcl's functionality, instead of reinventing it). which is shorter and simpler, but meddles more directly with the stack. The source code is compiled into bytecode, which is later interpreted by the Tcl interpreter. It just remains to check whether it does what we want. A matter of style and taste, in a way multable is 10 LOC and depends on nothing but Tcl, which is good; multable2 describes quite concisely what it does, and builds on a few other procs that are highly reusable. A math book showed me the Stirling approximation to n! Tcl/Tk for Programmers: With Solved Exercises that Work with Unix and Windows Memory Exercises: Memory Exercises Unleashed: Top 12 Memory Exercises To Remember Work And Life . An obvious string representation of a rational is of course "n/d". Here's the "bytecode engine" (ebc: execute byte code), which retrieves the implementations of bytecodes from the global array cmd: Let's now populate the bytecode collection. Another example, cooked up by myself this time, computes the average of a list. Tcl is a high-level language well suited for rapid development and prototyping. (Comm. The goto command is defined "locally", and deleted after leaving the state machine it is not meaningfully used outside of it. and wanted to bring it to life slightly adapted to Tcl style, especially by replacing the infix operator "o" with a Polish prefix style: Unlike procs or lambdas, more like APL or RPN, this definition needs no variables it declares (from right to left) what to do with the input; the result of each step is the input for the next step (to the left of it). If bitval is given, sets the bit at numeric position position to 1 if bitval != 0, else to 0; in any case returns the bit value at specified position. Nth Prime What's missing is the capability to randomly address parts of a stream, as is possible in Scheme (and of course their claim to do without assignment, or mutable data) Tcl lists just don't follow LISP's CAR/CDR model (though KBK demonstrated in Tcl and LISP that this structure can be emulated, also with procs), but rather C's flat *TclObject[] style. Only decades later, a hint in the Tcl chatroom pointed me to http://csc.smsu.edu/~shade/333/project.txt , an assignment to implement a Deterministic Turing Machine (i.e. After version 8.0/8.0, the unusually fast development of Tcl/Tk has slowed to a more normal pace. But this very soon crosses the limits of integers, giving wrong results. Create this and all subsequent Tcl exercise programs under your exercises/tcl subdirectory. For Joy's sets I haven't bothered yet they are restricted to the domain 0..31, probably implemented with bits in a 32-bit word. They think it's a programing (like software programing) and they are in VLSI Industry to do some hardware related job. and the experimental alpha version 8.1/8.1. A further optimization could be to tally value strings, and replace the frequent ones with "@$id", where db(@$id) holds the value once, and only db'get has to be adapted to redirect the query. For porting this, lmap is a good helper, even though not strictly functional: We furtheron borrow some more content from expr: We'll need functional composition, and here's a recursive de-luxe version that takes zero or more functions, hence the name o*: is the neutral element of variadic functional composition, when called with no functions at all. by one the binary operators +-*/. But the admittedly still very trivial challenge was met in truly function-level style, concerning the definitions of median, center and mean no variable left behind. Just say "Hello, World!". Unlike in earlier years when I was playing APL, this time my aim was not to parse and emulate J in Tcl I expected hard work for a dubitable gain, and this is a weekend fun project after all. This makes sense, even in Tcl, where one might implement them as. Task 1:- Input Output File Handling & Rearranging Data Step 1: Create a file and named it "file_input1.txt" (Content of "file_input1.txt" is given below - Remember, you have create file exactly same as given. Arguments are pushed on the stack, and the result of the "software", the stack at end, is returned. Learning Objectives The first two days of this course provide a . Other streams may provide a finite but very large number of elements, which would be impractical to process in one go. A collateral advantage is that all expressions are braced, without me having to care. Testing early and often is a virtue, as is documentation to make the following code snippets clearer, I tuned my little tester for better looks, so that the test cases in the source code also serve as well readable examples they look like comments but are code! TCL is string based scripting language and also a procedural language. Tcl was developed initially for Unix. Doing more steps towards functional programming, I came upon this interesting problem, and will shortly demonstrate that it can easily be solved in pure-Tcl. In Tcl, a sensible implementation for compact data storage would be as a list of lists. Once you've solved an exercise, submit it to our volunteer team, and they'll give you hints, ideas, and feedback on how to make it feel more like what you'd normally see in Tcl - they'll help you discover the things you don't know that you don't know. . * Edit and save ex1proc.tcl using the dosum proc and accompanying Tcl/Tk code from Tcl Syntax (procedures) Run ex1proc.tcl. Such process chains can be emulated in Tcl with the following rules: A stream is modelled here as a procedure that returns one stream item on each call. So here is one model of a state machine in ten lines of code. So let's get the pieces together. For instance, here's a breathtakingly short J program to compute the mean of a list of numbers: Only implicitly present is a powerful function combinator called "fork". In the algebra introduced here, with a variable "a", no further simplification was so far possible. In that situation, you can fall back to the (otherwise slower, and uglier) use of a dedicated iterator: But neither can you filter the keys you will get with a glob pattern, nor may you add or delete array elements in the loop the search will be immediately terminated. in a priority queue, the object with the highest priority comes first. They can be more precise than any "float" or "double" numbers on computers, as those can't exactly represent any fractions whose denominator isn't a power of 2 consider 13 which can not at any precision be exactly represented as floating-point number to base 2, nor as decimal fraction (base 10), even if bignum. But the program "dd" (which just duplicates the top of stack twice) has a stack balance of +2, and hence can never pass the example test. That's all. The first and second arguments are the class (disregarded here, as the dash shows) and the value, the rest is up to the coder. Of course, there are some who say: "Advocating object-orientated programming is like advocating pants-oriented clothing: it covers your behind, but often doesn't fit best" Quite a bunch of what is called OO can be done in pure Tcl without a "framework", only that the code might look clumsy and distracting. Try to swap the inputs: Another dirty trick: get square root of 4, add to 3 presto, 5. I won't go into all details of the above code, just some: (<.,>.) Tcl/Tk for Programmers is an introduction to the high-level Tcl/Tk scripting language for experienced programmers with either Unix or Windows background. Assume John Smith borrows "The Tempest". We have Boolean operators in expr, so here goes: The only unary operator NOT can be written in terms of nand: .. and everything else can be built from them too: Here's some testing tools to see whether an implementation is correct, look at its truth table, here done as the four results for A,B combinations 0,0 0,1 1,0 1,1 side note: observe how easily functions can be passed in as arguments: To see how efficient the implementation is (in terms of NAND units used), try this, which relies on the fact that Boolean functions contain no lowercase letters apart from the operator names: As a very different idea, having nothing to do with NAND as elementary function, the following generic code "implements" Boolean functions very intuitively, by just giving their truth table for look-up at runtime: Cryptarithms are puzzles where digits are represented by letters, and the task is to find out which. My oversimple implementation assumes that the operator is one that expr understands: which returns 28 just as Dr. Backus ordered (= 1*6 + 2*5 + 3*4). Tcl/Tk 8.2.3 and Tcl/Tk 8.3.0 under windows. And three nested calls to vec are sufficient to produce the divisors list:). It may be interesting to note that this language has truly minimal syntax the only rule is: each script ("word") composed of any number of bytecodes is well-formed. Tcl/Tk for Programmers is an introduction to the high-level Tcl/Tk scripting language for experienced programmers with either Unix or Windows background. Like in real life, test cases have to be carefully chosen. #-- Highlight the head position on the tape. $ mkdir ~/cs498gpl/exercises/tcl $ cd ~/cs498gpl/exercises/tcl. For instance, if the test has two inputs and wants one output, the stack balance is -1 (one less out than in). The code below also serves as usage example: }. Tcl is available for Linux, Windows, Mac OS X, as well as other platforms, as open-source software under BSD-like license, or as pre-built binaries. "Tacit programming" (tacit: implied; indicated by necessary connotation though not expressed directly) is one of the styles possible in J, and means coding by combining functions, without reference to argument names. The coin values should be passed to change as a variable number of arguments which are the coin values in units (e.g., a quarter would be represented as 25) in any order. Retrieving fields that may not physically exist needs a tolerant access function: In a classical database we have to define tables: which fields of what type and of which width. Tk is an extension, developed by the creator of Tcl, used for creating scripts that interact with users through windows. Tcl is used for web applications, desktop GUIs, testing and automation, and more. Ramanujan numbers: The pairs generator can be used to find Ramanujan numbers, which can be represented as the sum of two integer cubes in more than one way. I started with Backus' first Functional Program example. Core Python Programming, chapter 5 exercises number 5-3, question on this exercise. This chapter provides an overview of the Tcl syntax, data structures, and enough commands to develop applications. The partitioning helps very much in reducing the number of candidates. Tables are understood here as rectangular (matrix) arrangements of data in rows (one row per "item"/"record") and columns (one column per "field"/"element"). Clif is the author of the TclTutor package2 and the books Tcl/Tk for Real Programmers and Tcl/Tk: A Developer's Guide3. Implementation is as a "little-endian" list of integers, where bits 0..31 are in the first list element, 32..63 in the second, etc. Binary expr operators can be treated generically: Instead of enumerating all possible bytecode combinations beforehand (which grows exponentially by alphabet and word length), I use this code from Mapping words to integers to step over their sequence, uniquely indexed by an increasing integer. Of course, with growing databases we may reach memory limits: arrays need some extra storage for administration. Indexes are useful for repeated information that is likely to be searched. Transparent OO for Tcl, or TOOT for short, is a very amazing combination of Tcl's concept of transparent values, and the power of OO concepts. On the other hand, the present approach is pretty economic, since it does not use field widths (all strings are "shrink-wrapped"), and omits empty fields, while at the same time allowing to add whatever fields you wish. For instance, we want all books printed before 1980: We might also store our patrons in the same database (here in a different style): Without a concept of "tables", we can now introduce structures like in relational databases. If we give only this test, another solution is found: "Take x to the x-th" power" pow(0,0) gives indeed 1, but that's not the generic successor function. Exercism is fun, effective and The Tcl Programming Language is a comprehensive guide to Tcl, covering Tcl 8.6.. See the official book page for more information and a detailed Table of Contents.. Note that +/ is considered one operator, which applies the "adverb" folding to the "verb" addition (one might well call it "sum"). Creating a new syntax for a DSL would defeat the purpose of Tcl. This page is not available in other languages. The cute name "e.g." If any of the two operands is non-zero, then . Most of these example scripts first appeared in the Tclers' Wiki http://wiki.tcl.tk . The following scripts are plain Tcl, they don't use the Tk GUI toolkit (there's a separate chapter for those). #-- We need basic scalar operators from expr factored out: "length mismatch [llength $a]!= [llength $b]". Length: 3 days (24 Hours) Tcl has become the de facto standard embedded command language for Electronic Design Automation (EDA) applications. An important functional form is the conditional, which at Backus looks like. But bare-bones has its advantages too: in order to see how a clockwork works, you'd better have all parts visible:). Note that with this mapping, all valid programs (bytecode sequences) correspond to one unique non-negative integer, and longer programs have higher integers associated: Now out for discovery! A filter takes one or more streams, and possibly other arguments, and reacts like a stream too. This simple example invokes expr if the "command" is digestible for it: Imagine the makers of Tcl had failed to provide the if command. When J parses three operators in a row, gfh, where f is dyadic and g and h are monadic, they are combined like the following Tcl version does: In other words, f is applied to the results of applying g and h to the single argument. 7. For instance, if you would like to simplify the for loop, for the typical simple cases so you can write instead. Tcl is a powerful scripting language that runs under Unix, Linux, VMS, DOS/Windows, OS/2, and MacOS (at least). So to create such a table with a defined field structure, but no contents yet, one just assigns the header list: Note the double bracing, which makes sure tbl is a 1-element list. Any proc must however be called in compliance with Tcl's fundamental syntax: first word is the command name, then the arguments separated by whitespace. One point that was new for me is that the distinction between operators and operands is not cast in stone. First lmap is a collecting foreach it maps the specified body over a list: The following generic wrapper takes one binary operator (could be any suitable function) and two arguments, which may be scalars, vectors, or even matrices (lists of lists), as it recurses as often as needed. After some head-scratching, I find it plausible, and possibly it is even the simplest possible solution, given the poorness of this RPN language. This looks better to me than /slashing as in Postscript. As we've seen that x is true for any x, we can cancel out such tautologies. Running other programs from Tcl - exec, open Channel I/O: socket, fileevent, vwait More channel I/O - fblocked and fconfigure Communicating with other programs - socket, fileevent Time and Date - clock Using databases Introspection, Debugging and Performance Learning the existence of commands and variables - info State of the interpreter - info (One might truncate the list at front if it gets too long). The book includes a short introduction to TCP/IP, as well as longer introductions to writing client . The language is commonly used for rapid prototyping, scripted applications, GUIs, and testing. In the next step, I want to reimplement the "median" function, which for a sorted list returns the central element if its length is odd, or the mean of the two elements adjacent to the (virtual) center for even length. ", as it might also stand for factorial and see the shortest function body I ever wrote:^): Without big mention, functions implemented by recursion have a pattern for which func is well suited (see fac and gcd above). TCL Practice Task 3 (Scripting Language) TCL is very important from automation point of view in VLSI Industry but somehow students are not ready to learn this. It provides all the usual high-level programming features that we've come to expect from languages like the Unix shell, Awk, Perl, or Rexx, such as: Variable-length strings Associative arrays Lists For this, we reformat the expression to a list of values of type x or !x, that is in turn dumped into a local array for existence checking. To make things easier, this flavor of "software" is in a very simple RPN language similar to, but much smaller than, the one presented in Playing bytecode: stack-oriented like Forth, each operation being one byte (ASCII char) wide, so we don't even need whitespace in between. A program without such extravaganzas is shorter and yet does the same job, so it will have been tested earlier anyway. Different from switch, numbers are compared by numeric value, no matter whether given as decimal, octal or hex. Indexes: As shown, we can retrieve all data by sequential searching over array names. I'm far from having digested it all, but like so often, interesting reading prompts me to do Tcl experiments, especially on weekends. 100% free, forever. Get better at programming through fun, rewarding coding exercises that test your understanding of concepts with Exercism. Get better at programming through fun, rewarding coding exercises that test your understanding of concepts with Exercism. 1. J's "from" operator { takes zero or more elements from a list, possibly repeatedly. (!a || !b), but then again, these functions are equivalent. ): proc flatten_list { l } { if { [llength $l] == 0 } { return {} } elseif { [llength $l] == 1 && [lindex $l 0] == $l } { return $l } else { set ret {} As versatile as good old grep Persistence: Databases are supposed to exist between sessions, so here's how to save a database to a file: and loading a database is even easier (on re-loading, better unset the array before): If you use characters outside your system encoding (no problem to write Japanese book titles in Kanji), you'll have to fconfigure (e.g -encoding utf-8) on saving and loading, but that's just a few more LOC. The "machine" itself takes a list of alternating labels and state code; if a state code does not end in a goto or break, the same state will be repeated as long as not left, with goto or break (implicit endless loop). In other words, a tautology. with automatic analysis In a nutshell, his FP system comprises. being any pre- or user-defined function). I only had to take care that when moving beyond its ends, I had to attach a space (written as _) on that end, and adjust the position pointer when at the beginning. Before we start, a word of warning: maintaining state of a procedure is done with default arguments that may be rewritten. Book . It does so by adding the values of the hex digits: Stacks and queues are containers for data objects with typical access methods: In Tcl it is easiest to implement stacks and queues with lists, and the push method is most naturally lappend, so we only have to code a single generic line for all stacks and queues: It is pop operations in which stacks, queues, and priority queues differ: Priority (a number) has to be assigned at pushing time by pushing a list of two elements, the item itself and the priority, e.g.. To extend Tcl, i.e. The A formats can also be deduced from the following axioms: How much this ratio is, can easily be computed if we consider that A(n) is produced from A(n-1) by halving it parallel to the shorter side, so, So here is my Tcl implementation, which returns a list of height and width in centimeters (10000 cm2 = 1 m2) with two fractional digits, which delivers a sufficient precision of 1/10 mm: }. Let's change that "a" can have only two values, "" or <>, so we might try to solve the expression by assuming all possible values for a, and see if they differ. Without proof, I just claim that every function of n arguments whose characteristic integer is 2^(2^n) 1 is a tautology (or a true statement all bits are 1). But it looks halfway like the real thing: you get sort of an assembly listing with symbol table, and can run it I'd hardly start writing an assembler in C, but in Tcl it's fun for a sunny Sunday afternoon }, The mov b,INCR part is an oversimplification. Continuous, active development since the early 1990's. Write a function to determine if a list is a sublist of another list. Chapter 4 discusses Tcl I/O support for les, pipes, and sockets. So I tried with another a^2+b^2=c^2 set, and HEUREKA! Streams in general should not be written in brackets (then the Tcl parser would eagerly evaluate them before evaluating the command), but braced, and stream consumers eval the stream at their discretion. But I notice more and more that, on my way to functional programming, my proc bodies are a single call to expr which does all the rest (often with the powerful x?y:z operator). So, put the following source code in a test.tcl file. of your code and which, when called with no arguments, return 1 or 0, respectively. Adding a book to the database can be simply done by, Note that, as we never specified what fields a record shall contain, we can add whatever we see fit. Adding "records" to the table is as easy as. This can be plugged into a filter chain to see what's going on: # or, to get a stream of even numbers, starting from 0: "to recall is to call -- (1 || 1) == 1", "PONG [info hostname] [lindex [split $line] 1]", "Try http://wiki.tcl.tk/[lindex $args end]", "Why do [string map {I you my your your my you me} $args]? Called Logical OR Operator. But func isn't limited to math functions (which, especially when recursive, come out nice), but for expr uses in testing predicates as well: Exposing expr binary arithmetic operators as Tcl commands goes quite easy too: For "-", we distinguish unary and binary form: Having the modulo operator exposed, gcd now looks nicer: For unary not I prefer that name to "! This silly example demonstrates member access and some string manipulation: At university, I never learned much about Turing machines. For easier handling, it's a good idea to classify records somehow (we'll want to store more than books), so we add. Tcl is a popular and widely used cross-platform script programming language that achieves significant productivity gains when used by skilled engineers. Here is a simpler way that allows to extend unknown "in place" and incrementally: We let unknown "know" what action it shall take under what conditions. #--Another famous toy example, reading a file's contents: #--where Backus' selector (named just as integer) is here: #-- We need multiplication from expr exposed as a function: #-- And finally, iota is an integer range generator: #----- The dictionary has all one-liners: #------------------------ The test suite: #-- reading (varname $) and setting (varname set) global Tcl vars. It is however easy to build an interpreter for a language in Reverse Polish Notation (RPN) like Forth, Postscript, or Joy, and experiment with it. orders to, and bills from, booksellers) can be added with little effort, and cross-related also to external files (just set the value to the filename). On the other hand, Tk is a cross platform widget toolkit used for building GUI in many languages. Here is a simple example of a "chat bot" a program that listens on an IRC chatroom, and sometimes also says something, according to its programming. We have the patron's and book's ID in variables and do double bookkeeping: When he returns the book, the process is reversed: The dueback field (%Y-%M-%d format is good for sorting and comparing) is useful for checking whether books have not been returned in time: Likewise, parts of the accounting (e.g. This means that subsequent calls to know stack up, last condition being tried first, so if you have several conditions that fire on the same input, let them be "known" from generic to specific. Tcl 8.5 has the {*} construct to undo one-level of list packing (discussed on the Confluence page). Develop fluency in 67 programming languages personal mentoring, An alternative solution could involve recursion (if you can follow this, youre advanced! # Multiple documentation lines are allowed. Threads are for people who can't program state machines.". #-- a little tester reports the unexpected: #-- The test suite should silently pass when this file is sourced: # reports a proc's args and leading comments. TCL scripting is much sought after skill set for every VLSI engineer. Functions in Tcl are typically written with the proc command. The first formats a matrix (a list of lists to Tcl) with newlines and aligned columns for better display: Short again, and slightly cryptic, as is the "outer product" routine, which takes a function f and two vectors, and produces a matrix where f was applied to every pair of a x b in APL they had special compound operators for this job, in this case ".x": Again, lmap (the collecting foreach) figures prominently, so here it is in all its simplicity: With these parts in place, we can see that multable2 works as we want: So why write six procedures, where one did the job already? Chapter provides an overview of the above code, just some: <... Streams are a powerful concept in ( not only of this we get the integer... And yet does the same integer for for les, pipes, and!! Later interpreted by the Tcl syntax, data structures, and HEUREKA with a^2+b^2=c^2... Is done with default arguments that may be rewritten retrieve all data by sequential searching over array names:. Numeric value, no further simplification was so far possible integer of a rational is of ``... Programming in Tcl and Tk by Brent Welch, Ken Jones introductions to client. Are typically written with the proc command is compiled into bytecode, which at Backus looks like introduced here with... N'T go into all details of the above code, just some: ( <,... And yet does the same integer for deleted after leaving the state machine in ten lines code... Scripting is much sought after skill set for every VLSI engineer for rapid prototyping, scripted,... State machines. `` one point that was new for me is that the distinction between operators and is. Gui in many languages searching over array names based scripting language for experienced with. Code, just some: ( <., >. presto, 5 sequential searching over array names equivalent... Streams, and possibly other arguments, and sockets or Windows background the,... Which is shorter and simpler, but then again, these functions are equivalent { * construct. As decimal, octal or hex -- Highlight the head position on other... And HEUREKA was so far possible Confluence page ), test cases have to searched... Development of Tcl/Tk has slowed to a more normal pace number of elements, which would.. Tcl interpreter goto command is defined `` locally '', the object with the highest comes!, chapter 5 exercises number 5-3, question on this exercise a priority queue, the stack and... The algebra introduced here, with a variable `` a '', the.. Trick: get square root of 4, add to 3 presto, 5 8.5 has the { }... ' first functional program example we start, a sensible implementation for compact data storage be... Programmers is an introduction to the high-level Tcl/Tk scripting language for experienced Programmers with either Unix or Windows.. Your exercises/tcl subdirectory with another a^2+b^2=c^2 set, and more that was new for me that... New for me is that the distinction between operators and operands is not meaningfully used outside of.... For the typical simple cases so you can follow this, youre advanced dosum proc and accompanying Tcl/Tk from... Given as decimal, octal or hex weekend Tcl'ing and belatedly, Happy Birthday, John dirty trick: square! Comes first reacts like a stream too structures, and HEUREKA ) ex1proc.tcl. Of code productivity gains when used by skilled engineers or Windows background & quot ; me! Fun, rewarding coding exercises that test your understanding of concepts with Exercism the state machine it not. Gui toolkit ( there 's a separate chapter for those ) other hand, Tk is a platform! I/O support for les, pipes, and reacts like a stream too or 0,.... And simpler, but not only functional ) programming x is true for any,! Conditional, which is shorter and simpler, but then again, these are... Weekend Tcl'ing and belatedly, Happy Birthday, John for the typical simple cases so can... For rapid prototyping, scripted applications, GUIs, testing and automation, and testing `` locally '', testing... New for me is that the distinction between operators and operands is not used. Might implement them as of your code and which, when called with no arguments return! Is done with default arguments that may be rewritten course, with growing databases may. In the algebra introduced here, with growing databases we may reach memory limits: arrays need extra... Introduction to TCP/IP, as well as longer introductions to writing client DSL would defeat purpose! Rapid prototyping, scripted applications, desktop GUIs, testing and automation, and reacts like a stream.... A nutshell, his FP system comprises every VLSI engineer functional form is the associated integer of a is., Happy Birthday, John overview of the Tcl syntax, data structures, and enough commands to develop.... Introductions to writing client procedures ) Run ex1proc.tcl typically written with the proc command storage would be page ) of... Below also serves as Usage example: } gains when used by skilled engineers well suited rapid! Stream too scripted applications, desktop GUIs, testing and automation, and!... ' first functional program example may provide a finite but very large number of candidates demonstrates. If you can write instead `` a '', no matter whether given as decimal octal. An RPN language, hypot would be as a list, possibly repeatedly much after. The Tk GUI toolkit ( there 's a separate chapter for those ) x. Having to care no arguments, return 1 or 0, respectively trick: get square of... Sense, even in Tcl and Tk by Brent Welch, Ken.!: another dirty trick: get square root of 4, add to presto. Tk by Brent Welch, Ken Jones the object with the proc command get same. Indexes are useful for repeated information that is likely to be searched and operands is not cast stone! Inputs: another dirty trick: get square root of 4, add to presto. Compact data storage would be as a list is a high-level language well suited rapid! Exercises number 5-3, question on this exercise rewarding coding exercises that test your understanding concepts. Integer of a list is a popular and widely used cross-platform script programming language that achieves significant gains. Suited for rapid development and prototyping but not only functional ) programming is later interpreted by Tcl... Arrays need some extra storage for administration without me having to care to a more normal pace the! This and all subsequent Tcl exercise programs under your exercises/tcl subdirectory functions Tcl. As Usage example: } proc and accompanying Tcl/Tk code from Tcl syntax ( ). In Tcl are typically written with the stack, and reacts like a stream too myself this time, the... Get the same integer for as Usage example: more { grep this { cat streams.tcl } } given decimal. Be as a list, possibly repeatedly before we start, a word of warning: state... Developed by the creator of Tcl, used for web applications, desktop GUIs, testing automation... An overview of the two operands is not cast in stone if you can write.. The following source code is compiled into bytecode, which at Backus like! In ( not only of this we get the same job, so it will have been tested earlier.. Syntax, data structures, and sockets another example, cooked up by myself this time, computes the of. Typical simple cases so you can write instead applications, desktop GUIs, and deleted after leaving the state in. Save ex1proc.tcl using the dosum proc and accompanying Tcl/Tk code from Tcl syntax ( )! Tried with another a^2+b^2=c^2 set, and reacts like a stream too to undo one-level list... As shown, we can cancel out such tautologies one might implement them as are pushed on tape... And accompanying Tcl/Tk code from Tcl syntax ( procedures ) Run ex1proc.tcl cases so you can write instead, functions. No matter whether given as decimal, octal or hex possibly other arguments, enough! A short introduction to the table is as easy as me is that the distinction between operators and operands not. Set for every VLSI engineer construct to undo one-level of list packing discussed! Loop, for the typical simple cases so you can write instead with automatic in..., they do n't use the Tk GUI toolkit ( there 's a chapter. The high-level Tcl/Tk scripting language for experienced Programmers with either Unix or Windows background, where one might implement as. 1 or 0, respectively to produce the divisors list: ) mentoring, an alternative could. Some: ( <., >. proc command bytecode, which at Backus looks.! Are equivalent may provide a & & b, but not only this... Programming through fun, rewarding coding exercises that test your understanding of concepts with Exercism the inputs another! # Usage example: } for web applications, GUIs, testing and automation and. Written with the proc command a procedure is done with default arguments that be! Are braced, without me having to care cross platform widget toolkit used for scripts. Divisors list: ) array names 5 exercises number 5-3, question this! Reach memory limits: arrays need some extra storage for administration program without such extravaganzas is shorter and simpler but. Continuous, active development since the early 1990 's, no further simplification was far. On this exercise for the typical simple cases so you can follow this, youre!. Of course, with growing databases we may reach memory limits: arrays need some extra storage for administration programming... So, put the following source code is compiled into bytecode, which is later interpreted by the creator Tcl! Here, with growing databases we may reach memory limits: arrays need some storage. Be carefully chosen understanding of concepts with Exercism elements, which would be only of this we get same...

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